Cow slaugter is not mandatory but sacrificing a pet is the ritual not specifically a cow.... So as i said there should be mutual respect.
You are wrong not a "pet" but you see Cows and Camels are equal of 7 sheep so for one guy it is mandatory to sacrifice a sheep 7 guys can come together and sacrifice a cow or a camel which is cheaper and large families tend to do that for instance 7 brothers and sisters can come together and sacrifice one cow and the entire aspect of Eid is for families to come together so a lot of people choose to do that.

